Portable bed warmer

ABSTRACT

The invention provides a portable bed warmer comprising a housing provided with at least one heating element, in combination with a further component selected from the group consisting of a second heating element and a diode, as well as being provided with a blower for directing air to be heated by the elements; the housing being connected to at least one moisture-permeable, air impermeable, washable tube having a plurality of perforations, the tube being of sufficient length to extend along major portions of the periphery of a bed, on which it is positionable between a bottom sheet and a cover blanket to heat the space therebetween; the blower and heating element being operationally connected to thermostatically controlled regulating means for activating and deactivating the at least one heating element and maintaining the temperature passing through the tube at a predetermined level in the range of between 25-40° C.

The present invention relates to a portable bed warmer.

The prior art is replete with various bed-warming devices for home use, as well as specialized devices for raising and/or maintaining the body temperature of a sick patient.

Most people are familiar with electric blankets, which have low resistance electric coils passing therethrough for electrically heating a blanket placed over the user's body. People are also familiar with electric sheets, which are also provided with low resistance electric coils passing therethrough for electrically heating a bed before and/or during its use. Both of these types of bed warmers have the disadvantage of having occasionally been the cause of fires, which has led to a certain amount of public resistance to their use. There also exists the problem of laundering these products.

In order to overcome public resistance to the use of electric blankets and sheets, U.S. Pat. No. 4,777,802 provided a double-layer blanket assembly having an outer layer constructed of a relatively closely woven fabric for preventing air flow therethrough. Underneath the top layer is a second layer of material, edge-connected to the top layer, which is constructed of an air-permeable material such as, for example, relatively thin taffeta. A cavity exists between the two layers which receives pressurized cooled or heated air that passes through the air-permeable layer to cool or heat the user of the blanket assembly. A modified blanket assembly construction includes rigid edge wall members holding the outer and inner layers separated from each other at a predetermined spacing, thus reducing “pinch-off” between the layers which would restrict air flow within parts of the cavity or chamber. Peltier effect elements are selectively energizable to heat or cool air provided to the cavity of the blanket assembly.

Similarly, U.S. Pat. No. 4,867,230 provides a convection blanket for warming persons lying thereon. The preferred embodiment has four layers: two outer insulating layers and two inner layers of metallic foil. The inner metallic layers minimize heat loss across the length of the blanket. A unique pattern of pinholes in the top layers allows a larger volume of warm air to exit the blanket at the end opposite the air supply hose. All layers are stitched intermittently, without defining clear channels, to avoid distention of the blanket and assuring uniform distribution of air within the blanket.

An alternative solution is provided in European Patent Application No. 91403561.3, published under EP No. 0493267, in which heated air is circulated through a bed mattress.

Other patents deal with the warming of a patient covered with a special cover having air vents for heated air flow. Thus, e.g., U.S. Pat. No. 4,572,188 discloses an airflow cover for controlling the body temperature of a patient, covering a portion of the patient's body and providing a generalized thermal bathing of the covered portion through the delivery of a temperature-controlled gas mixture thereto. The cover is formed from a series of inflatable tubes which are joined together in a parallel array having an upper surface facing away from the patient's body and an oppositely directed lower surface, which faces the covered portion of the patient's body. An entry port is provided through the upper surface and into one tube, transverse ports open between the tubes, and exit ports are formed in the lower surface. A thermally controlled gas mixture is introduced through the entry port, circulates in the tubes by means of the transverse ports and inflates the tubes, and exits through the exit ports in the direction of the covered body portion, to provide the desired thermal bathing.

U.S. Pat. No. 4,660,388 discloses a cooling cover that has an air-inflatable pad which may be positioned within a pocket of a coverlet. The pad, formed of air-impermeable material, has plenum chambers at opposite ends thereof and a plurality of individual longitudinally extending passages extend between the plenum chambers. Openings or air orifices of a non-uniform pattern in the lower rounded surfaces of the inflatable pad direct cooling air in a plurality of small air jets onto the body of a user of the cooling cover. A source of cool air is connected to the inlet for a plenum chamber to deliver cool air to the pad.

In U.S. Pat. No. 5,300,100, there is described and claimed a body warmer, comprising a top panel having ends, the distance across the ends being the width of the panel, and sides, the distance along the sides being the length of the panel, a bottom panel having the same size and shape as the top panel, said panels each being a thin sheet of lightweight, permeable, pliant material, said top panel face-to-face with and contacting the bottom panel, said panels being joined together to form a plurality of tubular branches connected to a tubular trunk by a manifold, the manifold providing fluid communication between the trunk and the tubular branches, all of the branches being closed at one end of the panels, said trunk being open at the end of the panels opposite the end where the branches are closed, each tubular branch separated by a separation from adjacent tubular branches, adjacent branches remain proximate to each other at the ends of said branches joined to the manifold, and the separation between the tubular branches extends from the closed ends of said branches toward the manifold, so that said branches may be oriented farther apart from each other at the closed ends than at the ends joining the manifold.

The noticeable disadvantage of the above-described device is that it is only suitable for utilization during waking hours, or in patients lacking mobility. Otherwise, when a person moves or turns during his sleep, the distribution tubes will be blocked from distributing air flow due to weight on the tubes, thereby defeating the purpose of the warming device.

As stated in U.S. Pat. No. 5,300,100 (column 4, lines 58-61):

-   -   “This positioning is required because the body warmer 10 cannot         be unintentionally folded or kinked, since folds and kinds will         prevent the flow of air beyond the fold.”

Furthermore, as will be realized, these warmers, which are placed on the body, are uncomfortable to the use and are really intended for limited hospital use.

With the above-described state of the art in mind, there is now provided a portable bed warmer, comprising a housing provided with at least one heating element, in combination with a further component selected from the group consisting of a second heating element and a diode, as well as being provided with a blower for directing air to be heated by said elements;

said housing being connected to at least one moisture-permeable, air-impermeable, washable tube having a plurality of perforations, said tube being of sufficient length to extend along major portions of the periphery of a bed, on which it is positionable between a bottom sheet and a cover blanket to heat the space therebetween;

said blower and heating element being operationally connected to thermostatically controlled regulating means for activating and deactivating said at least one heating element and maintaining the temperature passing through said tube at a predetermined level in the range of between 25-40° C.

In preferred embodiments of the present invention, said tube is made of moisture-absorbing, washable Goretex®.

In especially preferred embodiments of the present invention, said further component is a diode.

Preferably, said housing is attached to a manifold feeding two tubes which diverge therefrom and then extend parallel to each other along the peripheral sides of the bed.

As will be realized, the bed warmer of the present invention has many advantages over those taught by the prior art.

First of all, provision of the perforated tubes along major portions of the periphery of the bed, instead of on top of the user, assures greater comfort and less chance of fouling, as well as rendering the device safe for use by children and the elderly. In addition, the tubes being made of moisture-permeable, washable material such as Goretex®, render the device user-friendly, both during incidental contact with the body of the user and in the context of the fact that the tubes can be readily disconnected, washed and reused periodically and frequently, together with the bed linen.

The bed warmer of the present invention is both safe and portable, and can be readily used in conjunction with any bed, at home or at vacation sites where electricity is readily available.

The device warms by convection rather than conduction, and due to the provision of a diode in circuit with a heating element or the provision of two heating elements which are independently thermostatically activated and inactivated, the cost of its operation can be kept low, since in preferred embodiments it operates at a wattage of less than 500 W, and in especially preferred embodiments, at less than 350 W.

The invention will now be described in connection with certain preferred embodiments with reference to the following illustrative figures so that it may be more fully understood.

With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

In the drawings:

FIG. 1 is a perspective view of a bed provided with a warming device according to the present invention;

FIG. 2 is a schematic representation of a blower, a heating element and control units in circuit with a diode according to the present invention; and

FIG. 3 is a schematic representation of the blower, two heating elements and control units of the warmer of the present invention.

There is seen in FIG. 1 a portable bed warmer 10. A housing 12 contains a heating element 14 and a blower 16 (seen in FIG. 2) for directing air to be heated by element 14.

Electric power is connected to the housing 12 by means of a cable 18. The housing 12 is shown positioned under the bed 20. The bed 20 contains no electric components of any type, thus assuring maximum safety.

The housing 12 generates hot air. The housing contents will be described with reference to FIG. 2.

A heated air outlet 22 of the housing 12 is connected to a moisture-permeable air-impermeable washable tube 24 having multiple perforations 26 for the discharge of warm air along its length. The tube 24 extends along major portions of the bed periphery. In the present embodiment the housing 12 is attached to a manifold 28 feeding two tubes 24 which diverge therefrom and then extend parallel to each other along the peripheral sides of the bed 20.

The tube 24 is advantageously positioned between a bottom sheet 30 and a cover blanket 32 and heats the space therebetween.

Suitably the tube 24 is made of a washable, moisture-absorbing material such as Goretex®.

With reference to the rest of the figures, similar reference numerals have been used to identify similar parts.

Referring now to FIG. 2, there is seen a diagrammatic representation of the electric components contained in housing 12. A heating element 14 is wired in series with a diode 34. A first thermostat 36 is connected in parallel to the diode 34.

The heater 14 operates in a low power mode, typically in the range 175 to 350 watt, as the diode 34 chops half of the AC wave. However if the air temperature sensed by the first thermostat 36 drops below 30 degrees C., the first thermostat 36 allows full current to flow by diverting current around the diode 34. Resulting full power, typically under 500 watt, is then available to the heater element 14.

If the air temperature sensed by the second thermostat 38 rises above 40 degrees C., the second thermostat 38 cuts off electric power to the complete system.

FIG. 3 illustrates an embodiment having two heating element 40, 42 connected in parallel, and a first 44 and a second thermostat 46. Normally the first heating element 44 operates to heat air blown thereon by blower 16. The main switch is shown at 50.

If the air temperature sensed by the second thermostat 46 drops below the first temperature set on the dial 48, the second thermostat 46 connects power to the second heating element 42, which then operates together with the first heating element 40.

If the air temperature sensed by the first thermostat 44 rises above the second temperature set on the dial 48, the first thermostat 44 cuts off electric power to the complete system.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. 

1. A portable bed warmer, comprising: a housing provided with at least one heating element, in combination with a further component selected from the group consisting of a second heating element and a diode, as well as being provided with a blower for directing air to be heated by said elements; said housing being connected to at least one moisture-permeable, air-impermeable, washable tube having a plurality of perforations, said tube being of sufficient length to extend along major portions of the periphery of a bed, on which it is positionable between a bottom sheet and a cover blanket to heat the space therebetween; said blower and heating element being operationally connected to thermostatically controlled regulating means for activating and deactivating said at least one heating element and maintaining the temperature passing through said tube at a predetermined level in the range of between 25-40° C.
 2. A portable bed warmer as claimed in claim 1, wherein said further component is a diode.
 3. A portable bed warmer as claimed in claim 1, wherein said tube is made of moisture-absorbing, washable Goretex®.
 4. A portable bed warmer as claimed in claim 1, wherein said housing is attached to a manifold feeding two tubes which diverge therefrom and then extend parallel to each other along the peripheral sides of the bed.
 5. A portable bed warmer as claimed in claim 1, said bed warmer operating at a wattage of less than 500 W.
 6. A portable bed warmer as claimed in claim 1, said bed warmer operating at a wattage of less than 350 W.
 7. A portable bed warmer as claimed in claim 1, wherein the temperature of the air passing through said tube is maintained at a predetermined level in the range of between 25-40° C. 